Invasive Species in Puerto Rico: The View From El Yunque

Abstract

Native flora and fauna of Puerto Rico have a long biogeographic connection to South America. Theory and empirical evidence suggest that islands, particularly those distantly isolated from the mainland, should be more susceptible to naturalizations and invasions of non-native species than continental areas. Anthropogenic disturbances can facilitate accidental and deliberate introductions of non-native species. In this study, we asked: What is the current status of introduced species within El Yunque National Forest (EYNF), the largest and most well-conserved forest area of Puerto Rico? To address this question, we reviewed the literature and surveyed local experts to identify introduced plant and animal taxa that are behaving as invaders within EYNF. We hypothesized that well-conserved forest areas within EYNF would be more resistant to invasions than disturbed areas along roads and ruderal areas with a long history of human activity. We found that there is only partial evidence that supports our hypothesis and this evidence is strongest in vascular plants, but not for the other taxonomic groups analyzed. Our combined results showed that currently the more ubiquitous invasive species in EYNF include some mammals (feral cat, rat, and mongoose) and some invertebrates (earthworms, mosquito, and Africanized honeybee). For many taxa, there is little information to thoroughly test our hypothesis, and thus more detailed surveys of the status of non-native and invasive species in EYNF are needed.

Hurricane Driven Changes in Vegetation Structure and Ecosystem Services in Tropical Urban Yards: a Study Case in San Juan, Puerto Rico

“…Additionally, it has been suggested that native species cope better with hurricane disturbances and have higher survival rates than non-native species (Brokaw et al 2012;Duryea et al 2007;Duryea and Kampf 2014). These differences in the responses of native and non-native species to hurricane damage could explain (at least in part) the high mortality rates observed in our yards that are dominated by non-natives and the relative lower mortality rates reported for natural forests, which are areas often dominated by native species or with lower proportion of non-native species than our yards (Ackerman et al 2017;Zimmerman et al 2021). However, more studies evaluating hurricane responses of native and non-native species in urban and natural forests are needed to understand the extent of these results.…”

Alien species affect the abundance and richness of native species in tropical forests: The role of adaptive strategies

“…These consequences may have profound impacts on the future of natural forests by altering successional regeneration and productivity, as well as the vulnerability, resilience, and capacity of the biota to adapt to climate change and altered disturbance regimes in which large‐scale, extreme events such as drought, tropical storms, and hurricanes are increasing. While well‐conserved tropical forests may be resistant to invasions by vascular plants (e.g., Ackerman et al, 2017; Zimmerman et al, 2021), we and others have shown that anthropogenically disturbed tropical forests can be quite vulnerable to biological invasions (Asner et al, 2008; Bempah et al, 2021; Rothstein et al, 2004) and that invasive alien species have the potential to severely alter the composition of tropical forests across different successional stages and have a long‐term impact on the abundance and richness of native species.…”

Invasive rodent responses to experimental and natural hurricanes with implications for global climate change

“…Black rats and house mice are two rodent species that occupy the Luquillo Experimental Forest (LEF) of northeastern Puerto Rico (Shiels & Ramírez de Arellano, 2018; Zimmerman et al, 2021). There are no extant native rodents in Puerto Rico, and the ecological roles of the three or more native rodent species that were in Puerto Rico's prehistoric fauna are largely unknown (Turvey et al, 2007).…”